Since the end of World War II in 1945, to one degree or another and on a far more regional scale, other conflicts have kept the globe in a constant state of political and military instability, fueling the fear that a dreaded third world war — one fought with nuclear weapons — may be just around the corner.

Some of these conflicts have been settled after much bloodletting. Most prominently, the fighting has ended, for the time being at least, in Korea, Vietnam, Sri Lanka and, closer to home, Northern Ireland and Cuba. Right now there’s the civil war in Syria and hugely dangerous unrest in Egypt, Nigeria and other parts of Africa, not to mention the other regionwide tensions in the Middle East and even Latin America.

But since the mid-’40s, there’s been one constant, a conflict that periodically erupts into open warfare but that even in peace appears destined to defy any solution. That, of course, is the conflict between Israel and its Arab neighbors, some of whom were displaced by the creation of Israel.

Since World War II, the United States has emerged as the world’s wealthiest, most powerful and most influential nation, a fact that has thrust Washington squarely into the middle of the seemingly intractable Israeli-Arab situation. It’s not a comfortable place to be.

It is probably unrealistic to expect that President Barack Obama’s visit to Israel this week might lead to a solution to such a long-standing situation, but if Obama weren’t to make the effort, the problems might only worsen.

And yet, writing in Sunday’s Washington Post, Aaron David Miller, vice president and distinguished scholar at the Woodrow Wilson International Center, sounded a note of optimism about the pending trip: “One presidential visit won’t forge a reconciliation … but increasing pressures to manage the Iranian nuclear issue, the peace process and (Prime Minister Benjamin) Netanyahu’s need to remain relevant in his new government just might.”

So the timing is encouraging. Both sides want Iran to be prevented from developing nuclear weapons, and Netanyahu’s domestic political needs could encourage him to show skeptics that he and Obama can work smoothly together.

“This odd couple’s ties are the most tenuous we’ve seen between the White House and Jerusalem,” wrote Miller, who served as a Middle East analyst, adviser and negotiator for Republican and Democratic secretaries of state from 1980 to 2003 and therefore has a greater knowledge of the situation than most.

“From the beginning, the Obama administration has prompted a batten-down-the-hatches mentality in Netanyahu’s circle — much the same way tough anti-settlement talk from President George H.W. Bush and Secretary of State James Baker worried Prime Minister Yitzhak Shamir,” he added.

Miller told how Netanyahu embarrassed Vice President Joe Biden by announcing a new housing project in East Jerusalem while Biden was on an official visit to Israel in 2010. (Because of Obama’s visit, the Israeli government postponed action on several East Jerusalem housing projects that can only heighten tensions with Palestinians.)

Later, on a visit to Washington, Netanyahu appeared to lecture Obama and made it clear he hoped Mitt Romney would be elected president. And Obama’s famous 2009 speech in Cairo, so widely applauded in the Arab world, was taken by many Israelis as a signal he would be unsympathetic to Netanyahu’s aggressive agenda.

This presidential trip may be saddled with more complexities than usual, but both sides must put aside their differences and pursue a shared goal, peace between Israel and its neighbors. The world is weary of this enduring threat to global stability.